A time-lapse photographing device has a configuration such that an observation object is photographed at intermittent photographing timings and an image of the observation object is acquired at each photographing timing, thereby making it possible to record images within an interval longer than that when the observation object is photographed as a dynamic image and perform reproduction within a short interval. In the time-lapse photographing device, the images obtained by photographing are usually directly saved, but when the observer is interested only in a change state of the observation object, saving the images within time intervals in which the observation object does not change becomes unnecessary. Accordingly, a device has been suggested (see Japanese Patent Application Laid-open No. 2004-309719) in which when the start operation of time-lapse photographing is performed, the actual photographing is not started, the photographing is started for the first time when the occurrence of a change in the observation object is detected, and the photographing is stopped when the observation object stops changing. With such a device, it is possible to view only the change state of the observation object by reproducing the saved images. Therefore, the processing speed of observation results can be greatly increased.